linux-kernel - Re: [PATCH][next] scsi: scsi_debug: remove a redundant assignment to variable ret

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Message-ID: <be932edb-33b8-4e99-b332-85bbfcaa904f@oracle.com>
Date: Thu, 17 Oct 2024 08:59:30 +0100
From: John Garry <john.g.garry@...cle.com>
To: Dan Carpenter <dan.carpenter@...aro.org>,
        Colin Ian King <colin.i.king@...il.com>
Cc: "James E . J . Bottomley" <James.Bottomley@...senpartnership.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        linux-scsi@...r.kernel.org, kernel-janitors@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] scsi: scsi_debug: remove a redundant assignment to
 variable ret

On 16/10/2024 08:16, John Garry wrote:
>>> scsi_debug.c
>>> @@ -3686,14 +3686,12 @@ static int do_device_access(struct 
>>> sdeb_store_info *sip, struct scsi_cmnd *scp,
>>>           sdeb_data_sector_lock(sip, do_write);
>>>           ret = sg_copy_buffer(sdb->table.sgl, sdb->table.nents,
>> You would think there would be a:
>>
>>     total += ret;
>>
>> here.
>>
>>>              fsp + (block * sdebug_sector_size),
>>>              sdebug_sector_size, sg_skip, do_write);T
>>>           sdeb_data_sector_unlock(sip, do_write);
>>> -        if (ret != sdebug_sector_size) {
>>> -            ret += (i * sdebug_sector_size);
>>> +        if (ret != sdebug_sector_size)
>>>               break;
>>> -        }
>>>           sg_skip += sdebug_sector_size;
>>>           if (++block >= sdebug_store_sectors)
>>>               block = 0;
>>>       }
>>>       ret = num * sdebug_sector_size;
>>          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> And that this would be a "return total;"
> 
> Right, the function is currently a little messy as there is no variable 
> for "total", and we re-assign ret per loop.
> 
> So I think that we can either:
> a. introduce a variable to hold "total"
> b. this change:
> 
> diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
> index af5e3a7f47a9..39218ffc6a31 100644
> --- a/drivers/scsi/scsi_debug.c
> +++ b/drivers/scsi/scsi_debug.c
> @@ -3690,13 +3690,14 @@ static int do_device_access(struct
> sdeb_store_info *sip, struct scsi_cmnd *scp,
>                 sdeb_data_sector_unlock(sip, do_write);
>                 if (ret != sdebug_sector_size) {
>                         ret += (i * sdebug_sector_size);
> -                       break;
> +                       goto out_unlock;
>                 }
>                 sg_skip += sdebug_sector_size;
>                 if (++block >= sdebug_store_sectors)
>                         block = 0;
>         }
>         ret = num * sdebug_sector_size;
> +out_unlock:
>         sdeb_data_unlock(sip, atomic);
> 
> 
> Maybe a. is better, as b. is maintaining some messiness.

BTW, let me know if you are happy for me to send a patch to fix this.

Thanks!